Ingot



Patented May 14, 1929.

UNITED STATES EMIL GATHMANN, 0F BALTIMORE, MARYLAND.l

INGOT.

Original application iled March 15, 1927, Serial No. 175,527. Dividedand this application led January 2o, 192s. serial No. 248.176.

The application for this patent. is a division of my application forpatent tiled'March 15, 1927. Serial No. 175,527, patented February 2S.1928. No. 1.661.039.

Thisinvention relates to the manufacture of ingots, the metal ot whichcontracts during soliditication from the molten to the -;solid, thehorizontal length and width of which ingots are materially greater thanthe vertical height. Such ingots are more economically reduced byJforging and rolling.; mill operations to plates, sheets and variousother units than are ingots made by the more widely used method ofso-called vert-ical casting.

Prior to my invention-ingots have been cast in what are known to thosefamiliar with the art as horizontal molds, i. e., molds-in which thelongitudinal axis of the mold chamber is disposed horizontally. In theuse of such molds, however. longitudinally extending pipes or shrinkagecavities have heen formed in the ingot, and in steel and other alloyedmetals cast in such molds segregation of the various elements hasoccurred to a dangerous degree, so that when the ingotis rolled intocommercial shapes or.units, some parts are sound and uniform whileothers are unsound or have Widely varying physical and chemicalcharacteristics, thus causing stresses to be set up in the semi-finishedproduct, which render it liable to break or split during the process ofmanufacture or in its use.

By my improvements I am enabled to produce an ingot of the horizontallycast type, which is free from pipe and shrinkage cracks and in which thesegregation may be to a great extent controlled. For certain products itis desirable to reduce segregation to a minimum, which I have madepossible by reducing the depth of the ingot relative to its width toinduce rapid freezing of the entire mass. For certain other products,such as boiler plate, segregation can be distributed substantiallyevenly over the upper plane of the ingot by providing any Well-knownmeans (such as coke dust, powdered graphite or the like spread upon thetop of the molten metal While the ingot is being cast) for retaining themetal molten at its upper surface for the desired length of time toobtain the amount of segregation required for the particular product.

The mold made in accordance with my invention preferably has a long,horizontallyarranged'major axis and a relatively nar'- rower transverseaxis. The height or depth of the mold chamber is less than its Width forreasons hereinafter explained. The side walls defining the ingot-formingchamber preferably gradually decrease in thickness upwardly and thebottom wall, which is relatively thicker or more heat-absorptive than-the side walls. is formed with a camber or have these characteristicsand/'the chamberV is properlvY dimensioncd, the freezing or@Asolidifying of the molten meta-l will be completed in less time for agiven mass ot metal than has heretofore been possible and the shrinkage:of the mass will be of such a character thatno pipe. is formed eitherat the top or at thek ends of the ingot and that segregation, due to therapid rate of soliditication of the molten metal, will be readilycontrolled.

My improvements are illustrated in the accompanying drawings, in which-Figure 1 is a perspective view of a. horizontal mold made in accordancewith my invention, portions of the mold being omitted for convenience ofillustration.

Figure 2 shows a vertical transverse section on lines 2 2 of Figure 1.

Figure 3 shows a section similar to that shown in Figure 2 with thesolidificdingot shown in cross section in the mold cavity.

Figure 4 shows a longitudinal section of the mold on lines 4t-4 otFigure 1 and illustrates also a longitudinal central section of theingot cast in the mold.

`Figure 5 is an enlarged view in perspective of a portion of the ingot.

Figure 6 is a perspective View of a portion ot a plate or sheet rolledfrom an ingot such as shown'in Figure 5.

The mold made in accordance with my i'nvention is preferably of castiron, which is commonly used inthe manufacture of various types of ingotmolds, the chamber Walls being formed as smooth as the state of the artpermits.

As is well-known to those skilled in the art, well deo'xidized moltensteel freezes and solidilies upwardly and inwardly from the mold chamberwalls, usually through formation of dendriticcrystals, untilsoliditication is complete.

In vertical vmolds of now well-known design, this solidifying process ofthe ingot is so controlled by means of big end up mold chambers andrefractory shrink head casings that the so-called pipe or shrinkagecavity is greatly reduced and confined to a -relatively small part ofthe ingot at its top. In the casting of ingots in horizontal molds,however, a decided shrinkage pipe, cavity or crevice has heretofore beenformed, which usually extends longitudinally from one end of the ingotto the other, being deepest and most pronounced near the center of themass of the ingot, which is always last to cool and solidify, at whichzone segregation is likewise concentrated.

By my invention I so shape the mold chamber that the molten metal of theingot will solidify in its central longitudinal portion in substantiallythe same period of time as the side or surrounding portions and theingot is so formed that what is known as cleavage cones and ingotism orthe formation of large crystals in the structure of the ingot aregreatly reduced. The bottom or base of the ingot surface being inwardlybellied or cambered to an extent proportional to the width and depth ofthe mold chamber and in ratio to the volume of the shrinkage of themetal forming the ingot during` solidification, the formation ofshrinkage cavities or pipes is prevented by compensating for and forcingthe contraction of the metal in vertical planes during soliditication. Aslightly dished or camber-ed portion at the upper face of the ingot issometimesformed therein, but concentrated shrinkage cavities or pipedzones are entirely prevented. In this way a great saving is effected, asthe percentage of sound metal which can be rolled or forged intocommercial shapesI is approximately the entire ingot, less only theusual scale and trimming loss of 4% to 6%.

An important feature of the invention is that the walls defining themold chamber are of such contour and heat absorptive quality that themolten metal will cool, solidify and shrink in a substantially verticaldirection from the bottom upward in approxin'iately the same period oftime at all vertical planes, as the depth of the liquid ingot metal inthe mold chamber at its central longitudinal port-ion is proportionatelyless and the cooling action of the mold walls greater than at adjacentportions of the chamber.

The drawings illustrate one way of constructing a mold in accordancewith my invention. The mold is made of cast iron of the kind usuallyemployed. The bottom B of the mold is relatively thick and heavy and theside walls A, which are materially thinner and less heat absorptive,gradually decrease in thickness vfrom their'lower to their upper ends,thus insuring that the soliditication of the molt-en metal of the ingotwill be progressively upwards, the same rule applying-in the formationof the side walls of the horizontal molds as applies in the formation ofside walls o'f vertical molds.

The bottom wall of my horizontal mold, however, diifers from the bottomwall of other molds. It will be observed that the bottom wall, inaddition to being relatively thick and heavy and thus more heatabsorptive than the side walls, is formed with a longitudinal rise orcamber X, which projects to its highest lpart at the central or middlelongitudinal portion of the mold cha-mber, so that as the molten metalcools, shrinks and solidiiies coincidently in the middle portion of themold with that of all adjoining portions, the entire mass of metalbecomes solidiiied without pipe or shrinkage cavity being formedtherein. The rise X may have various contours but is preferably camberedin the form of a convex arc as shown, the amount of this rise beinggoverned by the depth and width of mold chamber and the character of theingot metal for which the mold is designed.

As previously stated, the height of the mold chamber or that partthereof in which the casting is made, is less than its width. I havefound that the width should considerably exceed the depth of the chamberin order to obtain the best results. The exact ratio depends upon thetype of material being cast and the product for which the ingot isintended, e. g.. for low-carbon de-gassified steel, which soliditiesrelatively rapidly, a mold of the following dimensions might be used forsheet bar product.

If the width of the mold chamber at its top is l2, the greatest heightof the chamber should be approximately 8, while its height from the topof the rise X should be about 7". The over-all height of the mold shouldbe approximately 13, the distance from the bottom face of the mold tothe top of the rise X thus being about 6". The taper of the mold chamberfrom top to bottom should be approximately 1/2.

These relative dimensions have given satisfactory results in actualtest, but may and should be varied to correspond with specificconditions and requirements. The mold may be of any desired lengthwithin limitation. Any length to which the metal can flow without danger'of laps or cold shuts may be utilized.

It will be understood by those familiar with the artthat the liquidmetal of an ingot solidifying in a metallic mold is invariably hottestfor a longer period of time at the central or portions'of the ingotunless means are utilized to accelerate its cooling. B my improvementthere is less vertical height of ingot to cool at the center of the massthan at adjacent transverse parts, so that the rate of vertical cooling,within the limits specified, can be adjusted to obtain uniformsolidification. The method of teeming or pouring the meta-'l into myimproved type of mold and the stripping of the ingot therefrom is notapart of this invention. Various well-known methods have been foundsatisfactory.

Referring to Figure 5 of the drawings, I

have illustrated by dotted lines, a, I), c, and d, I

the manner in which solidification of the ingot occurs.

In Figure 6 of the drawings I have shown in perspective a portion of aplate showing the uniformly segregated zone portion in dotted lines,this portion having-been the last of the ingot to solidify.

, It will be observed that the ingot formed in the manner hereinbeforedescribed, has two primary side walls, that is, the bottom and top ofthe ingot, and four secondary walls, namely, the longitudinal sides, andthe ends. It will also be observed, by reference to Figure 5particularly, that all corners are well rounded. By such a constructionmost elieient heating and rolling can be obtained without danger ofburning or cracking dur- `ing these operations.

I claim as my invention: l. An ingot of slab-like contour, the depth ofwhich slab is less than its width or length,

one of the primary sides of larger area being concaved to a. depth ofnot over one-fourth but to at least one-eighth of the thickness of saidingot.

2. A horizontally-cast ingot, the length of which is greater than itswidth and the depth of which is less than its Width, one of the sides ofa larger area being concaved to a depth between one-eighth andone-fourth of the thickness of the ingot.

3. An ingot of slab-like contour formed of a metal that contracts involume during solidification, said ingot having a lengththat is greaterthan its width and a depth which is less than its width, one of thesides of larger area of said ingot being concaved to a depth of at leastone-eighth but not exceeding onefourth of the thickness of said ingot.l

4. A horizontally-cast ingot formed of a metal that contracts in volumeduring solidiication, the length of which is greater than its width andthe depth of which is less than its width, one of the sides of largerarea being concaved to an extent not exceeding onefourth of the depth ofthe ingot and the ingot throughout its entire structure being. free frompipe.

5. A horizontally-cast ingot formed of a metal that contracts in volumeduring solidification, the length of said ingot being greater than itswidth'and the width of the ingot being greater than'its depth and thebottom surface of the in got being formed of a concave o rinwardly-canibered contour, the depth of said concavity being more thanone-eighth, but less than one-fourth of the thickness of the ingot. o

6. A horizontally-cast ingot formed of a metal that contracts in volumeduring solidification, the length of said ingot being greater than itswidth and the width of which ingot is materially greater than itsthickness and the two major or primary surfaces of which is formed of aconcave or inwardly-cambered contour, the thickness of said ingot beingless at its central longitudinal section than at adjacent longitudinalportions. A

7. A horizontally cast ingot, the length of which is greater than itswidth and the depth of which is less than its width, both of the sidesoflarger area being concave, the width gf szlxid ingot being at leastfour times its 8. A long thin slag ingot having a shallow concaved lowerportion and a slightly eoncaved upper portion, the opposite sideportions of the ingot being inclined outwardly from bottom to top.

9. A long thin slab ingot having a shallow concaved lower portion and aslightly eon- .from bottom to top, an the four corners of said ingotbein rounded.

10. A metalllc ingot of slab-like contour,

the bottom of which is concaved in a curve of substantially uniformradius, the top of which ingot is slightly coneaved and the sides ofwhich are inclined outwardly from bottom 'to top.

scribed my name.

l EMIL GATHMANN.

